The fiscal 2013 defense authorization bill appears to be a likely candidate for Senate floor debate during the lame-duck session, with opening statements on the sprawling policy measure expected as early as the end of this week, a senior Senate Armed Services Committee aide said. But senators are discussing lots of possible amendments, and if there is no agreement to limit them, it could jeopardize the chances of clearing the bill this year

The current timeline would line up the bill (S 3254) for debate on amendments when senators return to Washington after Thanksgiving, allowing enough time for the Senate to conference its version of the measure with the House-passed bill (HR 4310) before the end of the 112th Congress.

The defense bill is third in the queue for the end-of-session legislative calendar, after a sportsmen bill (S 3525) and cybersecurity legislation (S 3414).

“We are confident the bill will receive floor time,” the committee aide said Tuesday.

Senate Armed Services Chairman Carl Levin, D-Mich., said Tuesday he would have just three days to debate the bill during the lame duck. He plans to work behind the scenes to whittle down the number of amendments offered during floor consideration.

But any effort to curtail debate on the bill would likely provoke strong backlash from Republicans, who are expected to offer amendments addressing issues ranging from the Obama administration’s response to the Sept. 11 attack on the U.S. consulate in Benghazi to language in the bill that would allow Defense Department funds to be used for abortions in the case of rape or incest.

If senators can reach an agreement on amendments, it would provide them with the smoothest path to clearing the bill, which has been signed into law every year for the last half-century. Lawmakers, however, have other legislative options, including bypassing the Senate floor and conferencing the Senate Armed Services Committee’s version of the measure with the House-passed bill.

If the defense bill does make it to the Senate floor, Iran will likely loom large during debate, as will the roughly $500 billion in across-the-board cuts that would hit the Pentagon budget starting Jan. 1, 2013, if Congress and the White House cannot agree to a deficit-reduction plan in the coming weeks.

Detainee policy, which consumed much of Senate floor debate last year on the fiscal 2012 authorization bill (PL 112-81) and nearly torpedoed its enactment, could also percolate once again.

The House’s version of the measure has already drawn a veto threat over several detainee-related provisions that administration officials are concerned could “challenge critical executive branch authority.” Those include language that would block the transfer of detainees from the military’s prison in Guantanamo Bay, Cuba.

The Senate Armed Services Committee’s version of the bill, which the panel approved in May, would extend by a year the certification requirements for the transfer of Guantanamo detainees to foreign countries and other foreign entities. Another provision would give a one-year extension to the restriction of funds available to the Defense Department to build any facility in the United States to house Guantanamo detainees.

But Sen. James M. Inhofe of Oklahoma, who is expected to become the Armed Services committee’s next top Republican, has said he is disappointed the bill does not contain an outright prohibition on the transfer of detainees from Guantanamo to U.S. soil.

That is “something that I will ensure is corrected when this bill comes to the floor,” Inhofe said in additional views included with the report that accompanies the defense bill.